biology vocab unit 3

gregor mendel

father of modern genetics - was interested in patterns of inheritance

allele

variation of a gene - slightly different versions of the protein - have a dominant and recessive one

dominant

alleles expressed when present

recessive

allele only expressed when received from both parents

genotype

the particular set of alleles carried by an individual

phenotype

an individual’s observable traits

homozygous

having identical alleles - AA or aa

heterozygous

having two different alleles - Aa

meiosis

special cell division, only occurs in reproductive organs, basis of sexual reproduction

fertilization

involves the fusion of reproductive cells (gametes-egg & sperm) from two parents

gametes

are haploid, they carry half of the parent’s DNA, 1 of each chromosome of the species

epistasis

affect a trait is influenced by products of multiple genes

pleiotrophy

single genes that influence multiple traits

codominance

two dominant allele - heterozygous individuals fully express both alleles

incomplete dominance

two dominant alleles - heterozygous phenotype is intermediate or blending between the two allele

punnett square

demonstrates the probability of the possible genotype and phenotype of offspring of crosses

genetic code

DNA sequence encoded as a gene that produces a RNA stand that codes for a protein (A, T, G, C)

transcription

process in the nucleus where a gene is transcribed (coped) from a DNA sequence into a strand of messenger RNA (mRNA) (A, U, G, C)

translation

mRNA is then translated into a protein at a ribosome (ribosomal RNA-rRNA)

pedigree

genetic family trees - used to study inheritance patterns in humans - shows whether a trait is associated with a dominant or recessive allele

sex chromosomes

the human X chromosome - every human has one - human Y chromosome - men have

hormones

chemical signals - governs the development of other sex-related characteristics

scrotum

a pouch of skin and smooth muscle holds the testes

epididymis

a coiled duct on top of the testes where the sperm mature

semen

sperm - fluids from three glands - bulbourethral glands, prostate gland, seminal vesicles

prostate gland

neutralizes acids of vagina

bulbourethral glands

cellars urethra of urine

seminal vesicles

sugar (energy for sperm) prostaglandins

vas deferens

a tube that carries sperm to an ejaculatory duct

stem cell

undifferentiated cell can divide and create more stem cells or differentiate to become a specialized cell type

horizontal gene transfer

genes transferred between individuals of the same generation

gene therapy

transfers a normal gene into an individual with the goal of treating a genetic defect or disorder from a mutated gene

genome

is a complete set of an organism’s DNA

fetus

from 9 weeks and birth

zygote

first diploid cell after fertilization - undergoes mitosis

menstruation

shedding of endometrium - only if pregnancy does not occur

ovary

produces eggs

oviduct (fallopian tubes)

tube extends from the uterus toward the ovary - site of fertilization

uterus (womb)

muscular chamber where fetus develop

cervix

region of uterus that connects to the vagina - mucus plug except during ovulation

vagina

opening for intercourse and birth canal - acidic, hostile to sperm

estrogen

triggers development of female sexual characteristics - readies the endometrium for implant

progesterone

maintains endometrium - inhibits ovulation

testosterone

testes - sperm production, sex drive, bone & muscle mass

corpus luteum

ruptured follicle from ovulation produces progesterone until implantation of embryo

implantation

begins around the sixth day when the blastocyst attaches and burrows into the endometrium

chorion

extraembryonic membrane of amniotes - chorionic villi form part of the placenta

placenta

organ composed of maternal and embryonic tissues that allows the exchange of materials between mother and embryo

human chorionic gonadotropin (HCG)

maintains the uterus to sustain a pregnancy - detected in home pregnancy tests

embryo

an unborn or unhatched offspring in the process of development

asexual reproduction

one parent

sexual reproduction

two parents

diploid

the presence of two complete sets of chromosomes in an organism's cells, with each parent contributing a chromosome to each pair

haploid

the presence of a single set of chromosomes in an organism's cells

homologous chromosomes

same size, same genes, different parents

crossover

mixes paternal and maternal alleles on homologous chromosomes

mRNA

carry the genetic information needed to make proteins

rRNA

part of the ribosome, or protein builders, of the cell

tRNA

a small RNA molecule that plays a key role in protein synthesis

nondisjunction

the failure of the chromosomes to separate

autosome

any chromosome that is not a sex chromosome

primary sexual characteristics

male are the penis, the scrotum, and the ability to ejaculate when matured. female primary sex characteristics are the vulva, vagina, uterus, fallopian tubes, cervix, and the ability to give birth and menstruate when matured

secondary sexual characteristics

enlarged breasts and widened hips of females, facial hair and adam's apples on males, and pubic hair on both

hormone

chemical signals that governs the development of other sex-related characteristics

ovaries

produce eggs

testes

sperm and testosterone

seminiferous tubules

testes filled with it - stem cells give rise to sperm - interstitial cells produce testosterone

therapeutic cloning

produces embryonic stem cells for experiments aimed at creating tissues to replace injured or diseased tissues

reproductive therapy

produces copies of whole animals